This section provides background information related to the present disclosure which is not necessarily prior art.
During a user communicating with another user through a mobile communication terminal, the user typically fails to hear clearly a session of the other user due to interference of a surrounding environment, or his or her hearing impairment, or the user may hear the session of the other user with such a high volume in a relatively quiet environment that he or she has to adjust manually the volume on his or her mobile communication terminal, thus degrading the experience of the user.
For example, a user A communicating with a user B may not hear clearly a session of the user B due to a noisy surrounding environment of the user A, so the user has to adjust manually the volume on his or her mobile communication terminal, where the session of the user B heard by the user A is referred to as an accepted session; and a session spoken out by the user A to the user B is referred to as a delivered session.